In 1903, revised plans drawn by Vernon for the Electric Light Station and Workshop now shows a two level structure facing George Street and a three levels high structure facing Hickson Road, with an octagonal chimney stack 60 metres (200 ft) in height on the northern side, and simple gabled roofs.

Between 1902 and 2004 the lower part of the building constructed on the site for a power station and workshops but and left unfinished and roofless, with the generating equipment never installed.

In 1987 refurbishment plans launched but later delayed until 1989, when the building was transferred to the Geological and Mining Museum Trust, and the name changed to The Earth Exchange.

The building is illustrative of the then debate on electricity supply, DC current being strongly, and stubbornly, supported by Thomas Edison.

It would appear that considerable bedrock has been excavated to George Street which is approximately three storeys above Hickson Road to facilitate the building on the site.

The Former Mining Museum and Chemical Laboratory building has a direct relationship with Circular Quay, George Street and Hickson Road.

[1] As at 30 March 2011, the Mining Museum and site are of State heritage significance for their historical and scientific cultural values.

It demonstrates the continuous significant human activity of collecting mineral and geological objects of economic and intellectual interest, carried out for almost 90 years on this site.

It is an excellent example of the Federation Warehouse style with good proportions and distinctive Romanesque and Art Nouveau detailing.

It is significant as an early 20th century museum building illustrating important external and internal design features.

[1] The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.

The subject site and building, particularly the chimney stack, is very prominent in The Rocks and Circular Quay and is distinctly a strong visual feature to the local area.

The subject site and building have a special cultural, social and educational value as a former Mining Museum and Chemical Laboratories, responsible for collecting, collating, displaying and researching minerals and geological objects.

[1] The place has potential to yield information that will contribute to an understanding of the cultural or natural history of New South Wales.

As an original planned D C Power Station and later as a constructed public institution - a mining museum and chemical laboratory.

[1] The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.